Electrical insulating knob



May 8, 1928. 4 1,668,581

D. Mei. BROWN ELEGTRI CAL INSULATING KNOB Filed Sept. 24, 1925 Patented May 8, 1928.

UNITED STATES PATENT OFFICE.

ELECTRICAL INSULATING KNOB.

Application filed September 24, 1925, Serial No. 58,420, and in Canada August 25, 1925.

My invention relates to improvements in insulating knobs in which these knobs can be screwed into wood surfaces by a wrench without theuse of a screw driver. Another special feature is the machine threaded top with nut to tighten the top half of knob down on the wires to be held in place.

I. attain these objects by the illustrations in the accompanying drawing, in which, Figure 1 is a side el vation of porcelain knob complete in two parts, with screw and nut; Fig. is a section through knob showing the two parts, and how the bottom half its into top half; Fig. 3 is a plan of lower half of knob at top; Fig. at is a plan of lower half at bottom; Fig. 5 is an elevation oi screw showing flattened piece in lower part of body and with machine thread top and screw thread at bottom; 6 is a plan of nut; Fig. 7 is it section through nut; Fig. 8 is a plan of screw at the pointed end.

Similar numerals refer to similar parts throughout the several views.

Fig. 1 represents the porcelain knob complete in two parts 1 and 2, screw 3 and not 4.

The top and lower halves of the porcelain knob have circular hole through the centre as at 5 in Figs. 2 and 3, and the bottom part o t top half 1 is recessed as at 6 in Fig. 2 to take the projection in top pnrt of lower hull 2 zit 'i' in Figs. 2 and also on e- :h side of the center oi lower halt of knob at the top a V shaped piece is cut out as iii) 9 which tits over V shaped piece cut out on each side of the center of top halt so or: to allow the wires to pass through and to keep them tightly in place when the top halt is scrcweiil down by nut l.

The lower half of lillfll) has a circulzi r hole through the center and ill this hole is wid ned out a. that. the shoulder screw nt 10, of l? u and so prevent new from being pushed up when knob is screwed ii; nny wood surface.

The threaded nut tightens the upper half of knob after the lower hall has been screwed into the Wooden surface.

I am aware that prior to my invention porcelain electrical insulating knobs have been made, I therefore do not claim such a. combination broadly, but,

What I do claim is 1. In an insulator an attaching means havlng lug screw one end, a clamping thread and nut at the other end, intermediate lateral projections formed just above the lag screw portion and a squure insulator body formed in two sections having a central opening extending through both sections, the lower part of said opening in the body portion having lateral extensions adapted to receive the luterul projections of the attzichin means whereby the body of the insulator may be used to force the attaching means into its support.

An insulator comprising a rectangular body ol vitreous material formed with a body portion and a cap portion, complementary conductor grooves tormed in the meeting faces of suid'portions, a centrally disposed, squared boss projecting from the meeting face of the body portion and complementary recess on the cap portion adapted to receive said boss, a centrally disposed opening extending completely through both portions, said opening having diametrically opposite extensions at the base ot the body portion, illl attaching member having wings adapted to lit the extensions of the central opening disposed within said opening, said attaching member having a lag screw portion extending beyond the body portion of the body and a threaded portion extending beyond the cup portion oi the body, and a clamping nut mounted on said threaded pori101].

In an insulator, an attaching means having a leg screw at one end, a clamping thread and nut at the other end, and having an 111- termediate projection, and an insulator body mounted on said attaching means having an opening to receive the same, said opening have a recess providing ashoulder against which said projection seats.

DONALD MQINTYRE BROWN. 

